I’m walking through an English woodland. The bluebells are beginning to flower and the cuckoos are calling. It really is a great time to be outdoors. Many of the overwintering insects are stirring and the air is filled with the buzz of queen bumblebees and the song of migrant birds. The English countryside is at its best.
However, as a medical entomologist working for Public Health England I am mindful of the fact that not all wildlife is quite so appealing. Spring and summer is peak time for ticks, and at this time of year much of my time is taken up studying them: their ecology, abundance and the diseases they transmit.
Ticks are becoming much more common now across large parts of England, particularly in woodlands, along woodland edges, on heathland and moorland and in some grassland sites. Their numbers are increasing largely due to the increase in deer numbers. Reports from the public about ticks in gardens are also increasing. With deer moving into urban areas and now becoming a more common feature in gardens, they are bringing ticks with them. This is surprising for many, particularly where they have only recently become a problem.
So, what are these ticks and what can we do to stop getting bitten by them? More to the point, why are ticks a health concern?
Ticks are blood-sucking members of the spider family. We have about 20 species in the UK and most of them feed on specific wild animals like bats, woodland birds, badgers and foxes. Several are only recorded from seabirds on offshore islands. In contrast though, the sheep or deer tick Ixodes ricinus feeds on practically all animals, including mammals, birds, reptiles, humans and pets (particularly dogs). This tick can be active all year, but numbers start to increase from late March, peaking in late spring and summer and will remain active until October.
The woodland that I’m walking through is perfect habitat for ticks. As well as providing a habitat for the animals they feed on, it also provides a moist microclimate for their survival. Ticks spend the majority of their three-year life in the leaf litter, trying to avoid drying out. Periodically, when the conditions are right, they climb up the vegetation and ‘quest’ for animals. They can sense the carbon dioxide we breathe out, the vibrations we make as we walk and our heat. Without eyes they don’t see us. If I reach down now and inspect the grasses and flowers of this woodland track I can actually see questing ticks. They are waving their front legs around, and if I get too close and brush the vegetation they will actually climb on.
They’re after my blood and they’ve probably been waiting quite a while. They will walk up my skin until they find an area like the back of my knees, my armpits, my waist or groin and begin to feed. It’s not pleasant but you don’t actually feel it. As a father of young children with a lust for the outdoors, I’m always mindful of ticks on them, particularly around the hairline.
As I walk through this woodland I’m making sure that I keep to the middle of path and trying to avoid overhanging vegetation. Ticks don’t jump or fly. If I do brush vegetation I’m making sure that I check my legs regularly to brush the ticks off. I’m wearing pale trousers so that I can see them better, and my trousers are tucked in my socks. Wellies are also a good defence.
The reason why I work on ticks and am keen to tell you about them is that they can transmit bacteria during feeding that causes Lyme borreliosis, or Lyme disease. The infection can be serious if not treated. Symptoms of Lyme disease can include a slowly expanding circular reddish rash, flu-like feeling, fatigue, muscle and joint pain. Most cases are cleared up with a course of antibiotics but without treatment, more serious conditions such as meningitis, facial palsy, nerve damage and arthritis can develop, so prevention and early detection are crucial. The best defences against Lyme are preventing tick bites, recognising the signs of infection and receiving prompt treatment, so in addition to my regular tick checks as I walk through this woodland I will check again when I get home to make sure I have removed any feeding ticks. Ticks are very small, so are not easy to see, although after a while you get your eye in. The nymph is the size of a freckle, and the larvae are even smaller and often go unnoticed.
When I speak to people in the countryside during field work I hear lots of theories about removing ticks, like covering them in Vaseline or nail varnish or burning them off. None of these are recommended as they can aggravate the tick and lead to secondary infection. I use a pair of fine tipped tweezers or a tick removal tool. The mouthparts of the tick are barbed and can be hard to remove, so a bit of force is required.
I’m leaving the woodland now, and I have been pretty diligent to remove any ticks from my trousers. My walk back to the road is along the edge of woodland and over some grassy fields. I’m still in tick habitat, so will check again before I get home. I always check at the end of a day in the countryside, and if I do find any ticks feeding I remove the tick promptly, clean the bite site with an antiseptic wipe and watch for any symptoms of Lyme disease, remembering to consult my GP if I feel unwell.
My group run a tick recording scheme and we are trying to map ticks across England to ensure that we can understand why and where they are increasing in numbers and to make sure we are alerting the public and GPs about tick awareness and tick-bite prevention. If you find a tick you can send it in to us for identification. We are also working in a range of habitats to understand what determines tick hotspots, how we can manage tick populations and what determines the prevalence of Lyme bacteria in the ticks. It’s worth remembering though that you don’t have to be in a bluebell wood to get ticks: urban parks and dog walking routes are also important habitats. Enjoy the countryside this spring, but try to remember to be tick aware.